1. Field of the Invention
The present invention relates to a method of cleaning a substrate processing apparatus that supplies a processing solution to a precision electronic substrate in the form of a thin plate (hereinafter simply called a “substrate”) such as a semiconductor water or a glass substrate for a liquid crystal display.
2. Description of the Background Art
A substrate processing apparatus conventionally employed in a process of manufacturing substrates performs surface processing of substrates including process with a chemical solution and rising process with de-ionized water, and subsequent drying process. Such a substrate processing apparatus includes an apparatus employing a single-wafer system of processing substrates one by one, and an apparatus employing a batch system of processing a plurality of substrates at the same time. Generally, the substrate processing apparatus of the single-wafer system performs process with a chemical solution by supplying a chemical solution to a surface of a rotating substrate, rinsing process with de-ionized water by supplying de-ionized water, and subsequent spin-drying process by causing the substrate to rotate at high speed. Such a substrate processing apparatus of the single-water system is disclosed for example in US 2008/0078428 and in Japanese Patent Application Laid-Open No. 2010-192686, for example.
The substrate processing apparatus disclosed in these publications includes a spin chuck causing a substrate to rotate held in a substantially horizontal position thereon, a nozzle from which a processing solution is supplied to the upper surface of the substrate held on the spin chuck, and a cup surrounding the spin chuck and provided to receive the processing solution scattered from the substrate. The apparatus disclosed in Japanese Patent Application Laid-Open No. 2010-192686 additionally includes a processing chamber housing these components, and a partition plate around the cup provided to divide the processing chamber into parts, one above the other.
This apparatus of the single-wafer system performs surface processing by supplying a processing solution to a rotating substrate, so the processing solution is scattered from the substrate by centrifugal force. Most of the scattered processing solution is collected in the cup surrounding the spin chuck. Meanwhile, part of the scattered processing solution converted into mist form may be scattered as far as to an outer wall surface of the cup or to surroundings of the cup, and then attached to the outer wall surface or the surroundings of the cup. This processing solution scattered outside the cup may become a source of pollution after it is dried.
So, the processing solution attached to the outer wall surface of the cup or to a member around the cup should be cleared where appropriate. The processing solution attached to the part outside the cup may be cleared by a special-purpose mechanism such as a nozzle from which de-ionized water is supplied to the part outside the cup or a nozzle from which nitrogen gas is sprayed for drying that is provided in addition to a nozzle for substrate processing. However, it is difficult to provide such a special-purpose mechanism in a substrate processing apparatus required to be reduced in size.